The invention refers to a system capable of converting bacterial reaction images into numerical values and analyzing microorganism growth by capturing images from a panel or plate.
The object of the invention consists in capturing and interpreting images produced by reactions taking place either in a liquid culture medium contained inside panel receptacles or on the surface of a solid culture medium in all-purpose laboratory receptacles, or so-called plates.
Liquid culture mediums use support means commonly referred to as panels which are usually made of polystyrene, have a rectangular shape and are fitted with receptacles designed to contain various microbiological culture mediums, biochemical substrates and/or antimicrobial agents in liquid form in which metabolic reactions occur, the microbiological interpretation of which leads to the identification of a microorganism and/or the definition of its capacity to be neutralized by one or several antibiotics.
The cultures may also be performed with the use of another type of support or plates in the form of a container generally made of polystyrene, having various shapes and containing a single solid culture medium on which the bacterial reaction takes place.
Thus, traditionally, in the case of the panels, a visual inspection of the reactions occurring the various receptacles is performed in the laboratory, and, based on the panels"" shape and color, the result probability is established according to general tables published for this purpose.
Automatic reading systems are presently used which, by measuring the optical density of the receptacles, assign a value interpreted as positive or negative by a computer program. Subsequently, another computer module establishes the result probability by combining the positive character of the partial reactions.
In the case of the plates, the approximation to the result has traditionally been more rudimentary in view of the smaller number of parameters involved, which are based mainly in the amount, size and color of the bacterial colonies.
The advantage of the these automatic systemsxe2x80x94which measure optical densitiesxe2x80x94over the traditional visual inspection method lies in that it eliminates the user""s subjectivity in interpreting reactions, since each reaction is translated into a numerical value.
However, these automatic systems present a serious problem and drawback in that they are unable to interpret both the morphological features and the growth patterns of the bacteria, which thus elude the result obtaining method of certain important elements, such as the form of bacterial growth, namely the base for obtaining microbiological results during the past decades.
The proposed system was conceived for the purpose of solving the above problems, allowing microbiological reactions to be converted to numerical values which are subsequently applied to a diagnosis software in order to establish the number of microorganisms present, revealing an infection, to identify the microorganisms present in the sample or to establish an organism""s antimicrobial susceptibility pattern.
The following reactions are identified via the inventive system:
Bacterial colony size, color, shape and quantity.
Color development in biochemical substrate receptacles, indicative of the type of bacterial metabolism involved.
Development of compact shapes or turbidness in antibiotic receptacles that would reflect the microorganism""s development capability in the presence of specific antimicrobial agent concentrations.
The formation of a circle around an antibiotic disc, or so-called xe2x80x9cinhibiting haloxe2x80x9d.
The system is thus based on a device preferably having a prismatic-rectangular shape, the inside of which establishes a hermetically closed chamber of diverse shapes and dimensions provided they allow for appropriate focal distance between a digital camera lens and the panel or plate to be analyzed. The digital camera is internally mounted on an upper central support, an internal area near the logier end of the chamber being fitted with a support associated to an inlet/outlet feeder arranged for depositing the corresponding panels or plates, i.e. the objects to be analyzed in each case, characteristic in that the supports are interchangeable and may be of various types depending on the panels or plates to be processed.
The function of this support installed inside the chamber, as previously stated, is to allow the passage of light from the lower part of the object being processed or analyzed, and to center the object under the digital camera.
An internal lighting system is also provided, comprising four fluorescent tubes, two of which are installed along the sides and above the object to be processed and the other two are installed under the object to be processed, so that, depending on the type of image to be processed, the upper, lower or both fluorescent lights are activated, this being implemented either automatically, through the function management software, or manually, by means of a switch.
Externally, the chamber""s front panel includes a series of function control LEDs and switches, in addition to the corresponding feeding mechanisms for inserting the panel or plate to be processed.
The chamber""s rear panel includes external outlets leading to a central computer, to a TDM 436 card and a to digital camera and lighting system power supply line; however, depending on the assembly""s operational requirements, other outlets may be installed or said outlets modified.
It must also be noted that the rear panel includes an access cover for internal cleaning, maintenance, component replacement, calibration, etc., purposes.
The system further includes a means of identifying the type of panel and the external data used for complementing the identification tests performed in the panel, and a means of establishing the position of each receptacle in the panel and calculating the panel area to be used for the reading.
According to the characteristics thus described, the system, in operation, must first perform a calibration of the camera by showing a camera histogram and its reading values on the screen of a control personal computer, so that, when an indicator lights up to signal the end of the calibration reading, a panel inserted in the internal support of the feeder may be read, said panel""s upper surface being divided into three information areas, namely one corresponding to the type of panel identification area, another corresponding to the external information area and a third corresponding to the receptacles area.
Once the corresponding reading option is activated in the control software, the feeder is closed and an image reading instruction is issued enabling the system-generated data to be interpreted by the software, which assigns the analyzed bacteria a taxonomic classification and a code as to whether it is resistant or not to a given antibiotic or group of antibiotics.